This invention relates in general to a lockset assembly, having a latchbolt movable between an open position and a deadbolt extended locked position, and more particularly, to a lockset assembly in which the latchbolt is prevented from returning to its deadbolt locked position when a locking member of the assembly is placed in an unlocked state.
A recent innovation in lockset assemblies involves the utilization of a single bolt to function both as a latchbolt, and as a deadbolt. An example of this type of lockset is illustrated in U.S. Pat. No. 4,594,864 and co-pending application, Ser. No. 799,555, filed Nov. 19, 1985 and assigned to the same assignee as the assignee hereof. The lockset assembly disclosed in said patent and patent application includes both inside and outside hand operated members to retract the latchbolt. The lockset is primarily designed for use on a door controlling egress from and ingress into a building.
Typically, the outside hand operated member is maintained in a locked position. A key is used to place a locking member in an unlocked state to enable the outside member to be used to move the latchbolt into a retracted or open position. Once the key is withdrawn from the lock cylinder, the latchbolt is preferably automatically returned to its deadbolt locked position. As the latchbolt is automatically placed into its deadbolt locked position when the key is removed from the locking mechanism, a lockset assembly including said latchbolt is not totally suitable for use in applications where it is desired to periodically prevent the latchbolt from automatically returning to its deadbolt locked position from an unlocked position. Examples of such applications are locksets used on the exterior of doors of school rooms, storage rooms, emergency exits, or the like.
For example, a school room door should be capable of being locked during non-school hours so that unauthorized access into the school room is prevented. On the other hand, when the school room is normally occupied, it is desirable to prevent the latchbolt from automatically returning into a deadbolt locked position from an unlocked state when a key operating the locking member is withdrawn therefrom. Essentially, during the occupied hours, the latchbolt is maintained in an unlocked state when the door is closed.
It should be understood that, regardless of the state of the latchbolt, i.e., either locked or unlocked, the inside operator must be capable of enabling a person located on the inside of the door to move the latchbolt into an unlocked or open position without the necessity of using a key or similar device. Movement of the latchbolt under control of the inside operator may be accomplished via a lever or by use of a push-bar exit device such as shown in U.S. Pat. No. 3,877,262 issued Apr. 15, 1975, Merton Williams, inventor.
Accordingly, it is an object of the invention to provide a lockset assembly wherein the latchbolt is normally in a deadbolt locked position and wherein the latchbolt is prevented from automatically returning to its deadbolt locked position when a locking member of the lockset is placed in an unlocked state.